1. Field of the Invention
The present invention relates to a process for reducing the emission of noxious gases from an automobile powered by a carburetor-equipped internal combustion engine during deceleration periods and to an apparatus for applying the same.
2. Description of the Prior Art
It is known that, despite attempts to improve the quality of carbureted mixtures delivered to an engine by one or more single or multi-barrel carburetors, it is difficult to obtain overall satisfactory results because of the overly high quantities of noncombusted fuel emitted during deceleration. Deceleration is understood to be any period where the driver of the vehicle has ceased all action by the accelerator on the butterfly gas valves and, while applying the brakes or not, allows the car to drive the engine through the transmission as normally set up, whether the transmission is an automatic gearbox or a classic mechanical gearbox with gears and clutch completely engaged.
It is also recognized that a considerable reduction in the amount of noncombusted fuel emitted in the exhaust gas during deceleration is obtained when the vacuum in the intake manifold is limited by an adjustment of the return position of the butterfly valve or valves when the pressure on the accelerator is ceased.
Various means are known and used which enable this vacuum limitation to be achieved by moving the closing stop of the butterfly valve in the direction of a wider opening. A first mechanism includes a membrane subjected to the vacuum of the engine, with the operation of the membrane being tied to the vacuum itself, for example, by means of a calibrated valve, so that it operates only above a certain value of vacuum.
Another improved device is remarkable in that the movable stop limiting the closing of the butterfly gas valves of the engine connected to an activation mechanism, whether vacuum operated, electromagnetic, or otherwise, in combination with a control mechanism operatively connected to a rotating element of the engine. The control mechanism and its connection with the rotating element are adapted in such a way that the activation mechanism acts to move the stop from its inactive rest position only when the speed of the engine is higher than a given minimum value.
In one embodiment, the activation mechanism includes an actuator placed, through a three-way solenoid valve, in communication with the atmosphere or with the intake manifold of the engine, while the control mechanism is either a centrifugal switch or other mechanism operatively connected to a tachymetric alternator driven by the crankshaft of the engine.
These prior art devices all have the drawback of being all-or-nothing systems, which reduces their efficiency.